1. Field of the Invention
The present invention relates to a dialyzing apparatus which can quickly remove water from blood of a patient who may have arteriosclerosis, without causing an abrupt blood-pressure decrease in the patient.
2. Related Art Statement
There is known a dialyzing apparatus which artificially removes, by utilizing osmotic-pressure difference or ultrafiltration, urea, uric acid, or creatinine, together with water, from blood of a patient. When the dialyzing apparatus is used, a patient whose blood circulates through the apparatus, and a doctor who attends to the patient cannot move away from the apparatus, for at least several hours. Therefore, it is desired to increase the water-remove rate and thereby quickly finish the dialysis operation. However, if the water-remove rate is excessively high, the patient may fall in a shock. To avoid this, an appropriate water-remove rate is manually set to obtain a target water amount to be removed for a dialysis duration of from 4 to 5 hours, in view of a standard body weight and a measured body weight of the patient and a water-remove capacity. The water-remove rate is defined as an amount of fluid that penetrates per unit time from the blood of the patient into the dialyzing fluid present in the dialyzer through the dialysis membrane, and the amount of fluid can be changed by changing a pressure difference over the dialysis membrane, e.g., a rotation speed of a negative-pressure pump which produces the pressure difference over the dialysis membrane.
Meanwhile, softness of arteries of a patient who has arteriosclerosis is low and accordingly, during a dialysis operation, blood pressure of the patient may abruptly decrease and fall in a shock. However, since it has been a conventional practice to set a water-remove rate irrespective of whether a patient has arteriosclerosis, there have been a considerably large number of cases where a patient who has arteriosclerosis fall in a shock during a dialysis operation.
It is therefore an object of the present invention to provide a dialyzing apparatus which can prevent a patient who may have arteriosclerosis, from falling in a shock during a dialysis operation.
The above objects have been achieved by the present invention. According to a first aspect of the present invention, there is provided a dialyzing apparatus comprising a dialyzer which removes water from blood of a patient at a water-remove rate; an arteriosclerosis-related-information obtaining device which obtains arteriosclerosis-related information that is related to a degree of arteriosclerosis of the patient; and a water-remove-rate display device which displays a target value of the water-remove rate based on the arteriosclerosis-related information obtained by the arteriosclerosis-related-information obtaining device.
Since the water-remove-rate display device displays the target value of the water-remove rate based on the arteriosclerosis-related information of the patient, a patient who may have arteriosclerosis can be prevented from falling in a shock during a dialysis operation, if the target water-remove rate displayed by the display device is set on the dialyzing apparatus. Thus, water can be quickly removed from blood of a patient who may have arteriosclerosis, without causing an abrupt blood-pressure decrease in the patient.
According to a preferred feature of the first aspect of the present invention, the dialyzing apparatus further comprises a target-water-remove-rate determining means for determining the target value of the water-remove rate based on the arteriosclerosis-related information obtained by the arteriosclerosis-related-information obtaining device, and the water-remove-rate display device displays the target value of the water-remove rate determined by the target-water-remove-rate determining means. If the target water-remove rate displayed by the display device is set on the dialyzing apparatus, a patient who may have arteriosclerosis can be prevented from falling in a shock during a dialysis operation. Thus, water can be quickly removed from blood of a patient who may have arteriosclerosis, without causing an abrupt blood-pressure decrease in the patient.
According to another preferred feature of the first aspect of the present invention, the target-water-remove-rate determining means determines a target water-remove rate range based on the arteriosclerosis-related information of the patient and a standard body weight and an actual body weight of the patient, and the water-remove-rate display device displays the determined target water-remove rate range. Preferably, the target-water-remove-rate determining means determines a lower target water-remove rate range corresponding to a higher degree of arteriosclerosis of the patient. If a value falling within the target water-remove rate range displayed by the display device, is set on the dialyzing apparatus, a patient who may have arteriosclerosis can be prevented from falling in a shock during a dialysis operation. Thus, water can be quickly removed from the blood of the patient who has arteriosclerosis, without causing an abrupt blood-pressure decrease in the patient.
According to another preferred feature of the first aspect of the present invention, the arteriosclerosis-related information may be a parameter which changes in relation with the degree of arteriosclerosis of the patient, e.g., pulse-wave-propagation-velocity-related information such as a pulse-wave propagation velocity or a pulse-wave propagation time measured to determine the velocity. The pulse-wave-propagation-velocity-related information may be obtained during a dialysis operation, e.g., immediately after the commencement of the dialysis operation but, preferably, the information is obtained before the commencement of the dialysis operation, most preferably, immediately before the commencement.
According to a second aspect of the present invention, there is provided a dialyzing apparatus comprising a dialyzer which removes water from blood of a patient at a pre-set water-remove rate; an arteriosclerosis-related-information obtaining device which obtains arteriosclerosis-related information that is related to a degree of arteriosclerosis of the patient; and a water-remove-rate changing means for changing the pre-set water-remove rate to a target water-remove rate based on the arteriosclerosis-related information obtained by the arteriosclerosis-related-information obtaining device.
Since the water-remove-rate changing means automatically changes the pre-set water-remove rate to the target water-remove rate based on the arteriosclerosis-related information of the patient, a patient who may have arteriosclerosis can be prevented from falling in a shock during a dialysis operation. Thus, water can be quickly removed from the blood of the patient who has arteriosclerosis, without causing an abrupt blood-pressure decrease in the patient.
According to a preferred feature of the second aspect of the present invention, the dialyzing apparatus further comprises a target-water-remove-rate determining means for determining the target water-remove rate based on the arteriosclerosis-related information obtained by the arteriosclerosis-related-information obtaining device, and the water-remove-rate changing means changes the pre-set water-remove rate to the target water-remove rate determined by the target-water-remove-rate determining means. Since the pre-set water-remove rate is automatically changed to the target water-remove rate based on the arteriosclerosis-related information of the patient, the patient who has arteriosclerosis can be prevented from falling in a shock during a dialysis operation. Thus, water can be quickly removed from the blood of the patient who has arteriosclerosis, without causing an abrupt blood-pressure decrease in the patient.
According to another preferred feature of the second aspect of the present invention, the target-water-remove-rate determining means determines a target water-remove-rate range based on the arteriosclerosis-related information of the patient and a standard body weight and an actual body weight of the patient, and the water-remove-rate changing means changes the pre-set water-remove rate to a value falling within the determined target water-remove-rate range. Since the pre-set water-remove rate is automatically changed to the target water-remove rate based on the arteriosclerosis-related information of the patient, the patient who has arteriosclerosis can be prevented from falling in a shock during a dialysis operation. Thus, water can be quickly removed from the blood of the patient who has arteriosclerosis, without causing an abrupt blood-pressure decrease in the patient.
According to another preferred feature of the second aspect of the present invention, the arteriosclerosis-related-information obtaining device comprises a pulse-wave-propagation-velocity-related-information obtaining device which obtains, as the arteriosclerosis-related-information, pulse-wave-propagation-velocity-related information that is related to a velocity at which a pulse wave propagates through an artery of the patient. Since the pre-set water-remove rate is automatically changed to the target water-remove rate or target water-remove rate range based on the pulse-wave-propagation-velocity-related information of the patient, the patient who has arteriosclerosis can be prevented from falling in a shock during a dialysis operation. Thus, water can be quickly removed from the blood of the patient who has arteriosclerosis, without causing an abrupt blood-pressure decrease in the patient.
According to another preferred feature of the second aspect of the present invention, the arteriosclerosis-related-information obtaining device comprises a pulse-wave-propagation-velocity measuring device which measures, as the arteriosclerosis-related-information, a pulse-wave propagation velocity at which a pulse wave propagates through an artery of the patient, and the target-water-remove-rate determining means determines, in a two-dimensional coordinate system which is defined by a first axis indicative of pulse-wave propagation velocity and a second axis indicative of water-remove rate, the target water-remove rate range based on the measured pulse-wave propagation velocity according to a pre-determined relationship between pulse-wave propagation and water-remove rate range. Preferably, the target-water-remove-rate determining means determines a lower target water-remove rate, or a lower target water-remove rate range, corresponding to a higher pulse-wave propagation velocity. Thus, water can be quickly removed from the blood of the patient who has arteriosclerosis, without causing an abrupt blood-pressure decrease in the patient.